1. Field of the Invention
The invention is in the field of Vitamin B.sub.12 derivatives. The unique properties of the cobamide molecule ("cobamide" used in the generic sense) and glutathione (GSH) are utilized to serve as a means of stabilizing and transporting persulfide sulfur (R-S-S.sup.-1).
2. Description of the Prior Art
Persulfide sulfur has recently been recognized has a regulator of cellular proliferation (1). Since low-molecular-weight persulfides are very unstable at pH near 7, the useful application of persulfides has previously required the use of systems which continuously generate persulfide sulfur in situ (1). Because of the complexity of these systems, it is desirable to replace them with a stable source of preformed persulfide sulfur.
The reaction of the sulfide, or hydrosulfide, ion with the cobalt atom of cobamide compounds has been reported (2-4). However, the Co-S bond is unstable and the compounds decompose rapidly in the presence of air to give the aquocobamide and colloidal sulfur. Sulfhydryl compounds (R-SH) also react in a similar manner to give somewhat more stable purple-colored derivatives (2,5). In the presence of air, these purple derivatives oxidize readily to regenerate the aquocobamide and the oxidized product R-S-S-R. The simultaneous addition of sulfide ion and GSH to a cobamide compound has not been previously reported and the unique stable product is novel.
It should be noted that Kaczka et al. reported a product from the reaction of H.sub.2 S with cyanocobalamin which, on exposure to air, reverted to a red compound with the properties of aquocobalamin (4). They stated that the red compound was found to contain sulfur by elemental analysis but that the sulfur was not detectable as sulfide, sulfite, or sulfate. This work is not reproducible and it is now clear that their red product was, in fact, aquocobalamin contaminated with super-fine colloidal sulfur which was not removed by filtration and which precipitated during crystallization of the cobalamin.